I can't remember whether Japanese is a 'sine qua non' requirement. From what I recall, it was an interesting strategy (simulation) game -- been a while since the last time I gave this one a spin. But if you're not comfortable with the genre, I suggest you stay away from it. Although you might enjoy it just for the neat T's soundtrack (Winds of Thunder, Sapphire...).
In the end, it's up to you and your wallet